Targeting molecular addictions in cancer

The construction and analysis of tricarboxylic acid cycle related prognostic model for cervical cancer

Introduction: Cervical cancer (CC) is the fourth most common malignant tumor in term of in incidence and mortality among women worldwide. The tricarboxylic acid (TCA) cycle is an important hub of energy metabolism, networking one-carbon metabolism, fatty acyl metabolism and glycolysis. It can be seen that the reprogramming of cell metabolism including TCA cycle plays an indispensable role in tumorigenesis and development. We aimed to identify genes related to the TCA cycle as prognostic markers in CC. Methods: Firstly, we performed the differential expressed analysis the gene expression profiles associated with TCA cycle obtained from The Cancer Genome Atlas (TCGA) database. Differential gene list was generated and cluster analysis was performed using genes with detected fold changes >1.5. Based on the subclusters of CC, we analysed the relationship between different clusters and clinical information. Next, Cox univariate and multivariate regression analysis were used to screen genes with prognostic characteristics, and risk scores were calculated according to the genes with prognostic characteristics. Additionally, we analyzed the correlation between the predictive signature and the treatment response of CC patients. Finally, we detected the expression of ench prognostic gene in clinical CC samples by quantitative polymerase chain reaction (RT-qPCR). Results: We constructed a prognostic model consist of seven TCA cycle associated gene (ACSL1, ALDOA, FOXK2, GPI, MDH1B, MDH2, and MTHFD1). Patients with CC were separated into two groups according to median risk score, and high-risk group had a worse prognosis compared to the low-risk group. High risk group had lower level of sensitivity to the conventional chemotherapy drugs including cisplatin, paclitaxel, sunitinib and docetaxel. The expression of ench prognostic signature in clinical CC samples was verified by qRT-PCR. Conclusion: There are several differentially expressed genes (DEGs) related to TCA cycle in CC. The risk score model based on these genes can effectively predict the prognosis of patients and provide tumor markers for predicting the prognosis of CC.

A CGA/EGFR/GATA2 positive feedback circuit confers chemoresistance in gastric cancer

De novo and acquired resistance are major impediments to the efficacy of conventional and targeted cancer therapy. In unselected gastric cancer (GC) patients with advanced disease, trials combining chemotherapy and an anti-EGFR monoclonal antibody have been largely unsuccessful. In an effort to identify biomarkers of resistance so as to better select patients for such trials, we screened the secretome of chemotherapy-treated human GC cell lines. We found that levels of CGA, the α-subunit of glycoprotein hormones, were markedly increased in the conditioned media of chemoresistant GC cells, and CGA immunoreactivity was enhanced in GC tissues that progressed on chemotherapy. CGA levels in plasma increased in GC patients who received chemotherapy, and this increase was correlated with reduced responsiveness to chemotherapy and poor survival. Mechanistically, secreted CGA was found to bind to EGFR and activate EGFR signaling, thereby conferring a survival advantage to GC cells. N-glycosylation of CGA at Asn52 and Asn78 is required for its stability, secretion, and interaction with EGFR. GATA2 was found to activate CGA transcription, whose increase, in turn, induced the expression and phosphorylation of GATA2 in an EGFR-dependent manner, forming a positive feedback circuit that was initiated by GATA2 autoregulation upon sublethal exposure to chemotherapy. Based on this circuit, combination strategies involving anti-EGFR therapies or targeting CGA with microRNAs (miR-708-3p and miR-761) restored chemotherapy sensitivity. These findings identify a clinically actionable CGA/EGFR/GATA2 circuit and highlight CGA as a predictive biomarker and therapeutic target in chemoresistant GC.

The role of next-generation sequencing in detecting gene FUSIONS with KNOWN and UNKNOWN partners: A single-center experience with methodologies' integration

AIMS

Next-generation sequencing (NGS) is becoming a new gold standard for determining molecular predictive biomarkers. This study aimed to evaluate the reliability of NGS in detecting gene fusions, focusing on comparing gene fusions with known and unknown partners.

METHODS

We collected all gene fusions from a consecutive case series using an amplicon-based DNA/RNA NGS platform and subdivided them into two groups: gene fusions with known partners and gene fusions with unknown partners. Gene fusions involving ALK, ROS1 and RET were also examined by immunohistochemistry (IHC) and/or fluorescent in situ hybridization (FISH).

RESULTS

Overall, 1174 malignancies underwent NGS analysis. NGS detected gene fusions in 67 cases (5.7%), further subdivided into 43 (64.2%) with known partners and 24 (35.8%) with unknown partners. Gene fusions were predominantly found in non-small cell lung carcinomas (52/67, 77.6%). Gene fusions with known partners frequently involved ALK (20/43, 46.5%) and MET (9/43, 20.9%), while gene fusions with unknown partners mostly involved RET (18/24, 75.0%). FISH/IHC confirmed rearrangement status in most (89.3%) of the gene fusions with known partners, but in only one (4.8%) of the gene fusions with unknown partners, with a significant difference (p<0.001). In 17 patients undergoing targeted therapy, the log-rank test revealed that the overall survival was higher in the known partner group than in the unknown partner group (p=0.002).

CONCLUSIONS

NGS is a reliable method for detecting gene fusions with known partners, but it is less accurate in identifying gene fusions with unknown partners, for which further analyses (such as FISH) are required.

PFKFB3 Inhibition Impairs Erlotinib-Induced Autophagy in NSCLCs

Tyrosine kinase inhibitors (TKIs) targeting the kinase domain of the epidermal growth factor receptor (EGFR), such as erlotinib, have dramatically improved clinical outcomes of patients with EGFR-driven non-small cell lung carcinomas (NSCLCs). However, intrinsic or acquired resistance remains a clinical barrier to the success of FDA-approved EGFR TKIs. Multiple mechanisms of resistance have been identified, including the activation of prosurvival autophagy. We have previously shown that the expression and activity of PFKFB3—a known driver of glycolysis—is associated with resistance to erlotinib and that PFKFB3 inhibition improves the response of NSCLC cells to erlotinib. This study focuses on investigating the role of PFKFB3 in regulating erlotinib-driven autophagy to escape resistance to erlotinib. We evaluated the consequence of pharmacological inhibition of PFKFB3 on erlotinib-driven autophagy in NSCLC cells with different mutation statuses. Here, we identify PFKFB3 as a mediator of erlotinib-induced autophagy in NSCLCs. We demonstrate that PFKFB3 inhibition sensitizes NCSLCs to erlotinib via impairing autophagy flux. In summary, our studies uncovered a novel crosstalk between PFKFB3 and EGFR that regulates erlotinib-induced autophagy, thus contributing to erlotinib sensitivity in NSCLCs.

TGFβ2-mediated epithelial-mesenchymal transition and NF-κB pathway activation contribute to osimertinib resistance

Osimertinib (AZD9291) has been widely used for the treatment of EGFR mutant non-small cell lung cancer. However, resistance to osimertinib is inevitable. In this study we elucidated the molecular mechanisms of resistance in osimertinib-resistant NCI-H1975/OSIR cells. We showed that NCI-H1975/OSIR cells underwent epithelial-mesenchymal transition (EMT), which conferred sensitivity to the GPX4 inhibitor 1S, 3R-RSL3 to induce ferroptotic cell death. The EMT occurrence resulted from osimertinib-induced upregulation of TGFβ2 that activated SMAD2. On the other hand, we revealed that NCI-H1975/OSIR cells were highly dependent on NF-κB pathway for survival, since treatment with the NF-κB pathway inhibitor BAY 11-7082 or genetic silence of p65 caused much greater cell death as compared with the parental NCI-H1975 cells. In NCI-H1975 cells, osimertinib activated NF-κB pathway, evidenced by the increased p65 nuclear translocation, which was abolished by knockdown of TGFβ2. In the cancer genome atlas lung adenocarcinoma data, TGFB2 transcript abundance significantly correlated with EMT-associated genes and NF-κB pathway. In addition, coexistence of EMT and activation of NF-κB pathway was observed in several NCI-H1975/OSIR clones. These findings shed new light on distinct roles of TGFβ2 in osimertinib-resistant cells and provide new strategies for treatment of this resistant status.

A cytoskeleton regulator AVIL drives tumorigenesis in glioblastoma

Glioblastoma is a deadly cancer, with no effective therapies. Better understanding and identification of selective targets are urgently needed. We found that advillin (AVIL) is overexpressed in all the glioblastomas we tested including glioblastoma stem/initiating cells, but hardly detectable in non-neoplastic astrocytes, neural stem cells or normal brain. Glioma patients with increased AVIL expression have a worse prognosis. Silencing AVIL nearly eradicated glioblastoma cells in culture, and dramatically inhibited in vivo xenografts in mice, but had no effect on normal control cells. Conversely, overexpressing AVIL promoted cell proliferation and migration, enabled fibroblasts to escape contact inhibition, and transformed immortalized astrocytes, supporting AVIL being a bona fide oncogene. We provide evidence that the tumorigenic effect of AVIL is partly mediated by FOXM1, which regulates LIN28B, whose expression also correlates with clinical prognosis. AVIL regulates the cytoskeleton through modulating F-actin, while mutants disrupting F-actin binding are defective in its tumorigenic capabilities.

Genes that modulate the cytoskeleton have been associated with increased cell proliferation and migration. Here, the authors show that AVIL, an actin regulatory protein, is overexpressed in glioblastomas and mediates oncogenic effects through regulation of FOXM1 stability and LIN28B expression.

Maintaining protein stability of ∆Np63 via USP28 is required by squamous cancer cells

The transcription factor ∆Np63 is a master regulator of epithelial cell identity and essential for the survival of squamous cell carcinoma (SCC) of lung, head and neck, oesophagus, cervix and skin. Here, we report that the deubiquitylase USP28 stabilizes ∆Np63 and maintains elevated ∆NP63 levels in SCC by counteracting its proteasome-mediated degradation. Impaired USP28 activity, either genetically or pharmacologically, abrogates the transcriptional identity and suppresses growth and survival of human SCC cells. CRISPR/Cas9-engineered in vivo mouse models establish that endogenous USP28 is strictly required for both induction and maintenance of lung SCC. Our data strongly suggest that targeting ∆Np63 abundance via inhibition of USP28 is a promising strategy for the treatment of SCC tumours.

Increased 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-3 activity in response to EGFR signaling contributes to non-small cell lung cancer cell survival

Constitutive activation of the epidermal growth factor receptor (EGFR) because of somatic mutations of the EGFR gene is commonly observed in tumors of non-small cell lung cancer (NSCLC) patients. Consequently, tyrosine kinase inhibitors (TKI) targeting the EGFR are among the most effective therapies for patients with sensitizing EGFR mutations. Clinical responses to the EGFR-targeting TKIs are evaluated through 2-[¹⁸F]fluoro-2-deoxy-glucose (¹⁸FDG)-PET uptake, which is decreased in patients responding favorably to therapy and is positively correlated with survival. Recent studies have reported that EGFR signaling drives glucose metabolism in NSCLC cells; however, the precise downstream effectors required for this EGFR-driven metabolic effect are largely unknown. 6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3) is an essential glycolytic regulator that is consistently overexpressed in lung cancer. Here, we found that PFKFB3 is an essential target of EGFR signaling and that PFKFB3 activation is required for glycolysis stimulation upon EGFR activation. We demonstrate that exposing NSCLC cells harboring either WT or mutated EGFR to EGF rapidly increases PFKFB3 phosphorylation, expression, and activity and that PFKFB3 inhibition markedly reduces the EGF-mediated increase in glycolysis. Furthermore, we found that prolonged NSCLC cell exposure to the TKI erlotinib drives PFKFB3 expression and that chemical PFKFB3 inhibition synergizes with erlotinib in increasing erlotinib's anti-proliferative activity in NSCLC cells. We conclude that PFKFB3 has a key role in mediating glucose metabolism and survival of NSCLC cells in response to EGFR signaling. These results support the potential clinical utility of using PFKFB3 inhibitors in combination with EGFR-TKIs to manage NSCLC.

Dichloroacetate Affects Mitochondrial Function and Stemness-Associated Properties in Pancreatic Cancer Cell Lines

Targeting metabolism represents a possible successful approach to treat cancer. Dichloroacetate (DCA) is a drug known to divert metabolism from anaerobic glycolysis to mitochondrial oxidative phosphorylation by stimulation of PDH. In this study, we investigated the response of two pancreatic cancer cell lines to DCA, in two-dimensional and three-dimension cell cultures, as well as in a mouse model. PANC-1 and BXPC-3 treated with DCA showed a marked decrease in cell proliferation and migration which did not correlate with enhanced apoptosis indicating a cytostatic rather than a cytotoxic effect. Despite PDH activation, DCA treatment resulted in reduced mitochondrial oxygen consumption without affecting glycolysis. Moreover, DCA caused enhancement of ROS production, mtDNA, and of the mitophagy-marker LC3B-II in both cell lines but reduced mitochondrial fusion markers only in BXPC-3. Notably, DCA downregulated the expression of the cancer stem cells markers CD24/CD44/EPCAM only in PANC-1 but inhibited spheroid formation/viability in both cell lines. In a xenograft pancreatic cancer mouse-model DCA treatment resulted in retarding cancer progression. Collectively, our results clearly indicate that the efficacy of DCA in inhibiting cancer growth mechanistically depends on the cell phenotype and on multiple off-target pathways. In this context, the novelty that DCA might affect the cancer stem cell compartment is therapeutically relevant.

Ezh2 inhibition in Kras-driven lung cancer amplifies inflammation and associated vulnerabilities

Kras-driven non–small-cell-lung cancers (NSCLCs) are a leading cause of death with limited therapeutic options. Serresi et al. show that inhibiting Ezh2 in orthotopic KrasG12D-driven NSCLC unleashes an inflammatory response rewiring tumor progression and amplifying associated vulnerabilities that could be therapeutically exploited.

Kras-driven non–small-cell lung cancers (NSCLCs) are a leading cause of death with limited therapeutic options. Many NSCLCs exhibit high levels of Ezh2, the enzymatic subunit of polycomb repressive complex 2 (PRC2). We tested Ezh2 inhibitors as single agents or before chemotherapy in mice with orthotopic Kras-driven NSCLC grafts, which homogeneously express Ezh2. These tumors display sensitivity to EZH2 inhibition by GSK126 but also amplify an inflammatory program involving signaling through NF-κB and genes residing in PRC2-regulated chromatin. During this process, tumor cells overcome GSK126 antiproliferative effects. We identified oncogenes that may mediate progression through an in vivo RNAi screen aimed at targets of PRC2/NF-κB. An in vitro compound screening linked GSK126-driven inflammation and therapeutic vulnerability in human cells to regulation of RNA synthesis and proteostasis. Interestingly, GSK126-treated NSCLCs in vivo also showed an enhanced response to a combination of nimesulide and bortezomib. Thus, Ezh2 inhibition may restrict cell proliferation and promote defined adaptive responses. Targeting these responses potentially improves outcomes in Kras-driven NSCLCs.

ETS-targeted therapy: can it substitute for MEK inhibitors?

BACKGROUND

The RAS/MAPK pathway has been intensively studied in cancer. Constitutive activation of ERK1 and ERK2 is frequently found in cancer cells from a variety of tissues. In clinical practice and clinical trials, small molecules targeting receptor tyrosine kinases or components in the MAPK cascade are used for treatment. MEK1 and MEK2 are ideal targets because these enzymes are physiologically important and have narrow substrate specificities and distinctive structural characteristics. Despite success in pre-clinical testing, only two MEK inhibitors, trametinib and cobimetinib, have been approved, both for treatment of BRAF-mutant melanoma. Surprisingly, the efficacy of MEK inhibitors in other tumors has been disappointing. These facts suggest the need for a different approach. We here consider transcription factor ETS1 and ETS2 as alternate therapeutic targets because they are major MAPK downstream effectors.

MAIN TEXT

The lack of clinical efficacy of MEK inhibitors is attributed mostly to a subsequent loss of negative feedback regulation in the MAPK pathway. To overcome this obstacle, second-generation MEK inhibitors, so-called "feedback busters," have been developed. However, their efficacy is still unsatisfactory in the majority of cancers. To substitute ETS-targeted therapy, therapeutic strategies to modulate the transcription factor in cancer must be considered. Chemical targeting of ETS1 for proteolysis is a promising strategy; Src and USP9X inhibitors might achieve this by accelerating ETS1 protein turnover. Targeting the ETS1 interface might have great therapeutic value because ETS1 dimerizes itself or with other transcription factors to regulate target genes. In addition, transcriptional cofactors, including CBP/p300 and BRD4, represent intriguing targets for both ETS1 and ETS2.

CONCLUSIONS

ETS-targeted therapy appears to be promising. However, it may have a potential problem. It might inhibit autoregulatory negative feedback loops in the MAPK pathway, with consequent resistance to cell death by ERK1 and ERK2 activation. Further research is warranted to explore clinically applicable ways to inhibit ETS1 and ETS2.

Role of the pretreatment 18F-fluorodeoxyglucose positron emission tomography maximal standardized uptake value in predicting outcomes of colon liver metastases and that value's association with Beclin-1 expression

The current study sought to evaluate the predictive and prognostic performance of the maximum standardized uptake value (SUV_max) prior to treatment in 43 patients with colon cancer and unresectable liver metastases. Patients with colon cancer who underwent ¹⁸F-FDG-PET/computed tomography (CT) scans for staging before the start of first-line 5-fluorouracil-based chemotherapy were retrospectively analyzed. Expression of Beclin-1 in cancer cells was evaluated in primary tumors using immunohistochemical staining. The pretreatment SUV_max for liver metastases was not able to predict progression-free survival but was significantly associated with poorer overall survival, with a hazard ratio of 2.05 (95 % CI, 1.016-4.155). Moreover, a negative correlation was noted between SUV_max and expression of a marker of autophagy - Beclin-1 (rho = -0.42, p = 0.006). This suggests that the pretreatment SUV_max in ¹⁸F-FDG PET/CT is a useful tool to help predict survival outcome in patients with colon cancer and unresectable liver metastases and may significantly distinguish between patients with low and high levels of Beclin-1 expression (AUC = 0.809, 95% CI: 0.670-0.948, p = 0.001).

Validation of a next generation sequencing panel for detection of hotspot cancer mutations in a clinical laboratory

Recent advances in sequencing technologies have enabled us to scrutinize the versatile underlying mechanisms of cancer more precisely. However, adopting these new sophisticated technologies is challenging for clinical labs as it involves complex workflows, and requires validation for diagnostic purposes. The aim of this work is towards the analytical validation of a next generation sequencing (NGS) panel for cancer hotspot mutation analysis. Characterized formalin-fixed paraffin-embedded (FFPE) samples including biopsy specimens and cell-lines were examined by NGS methods utilizing the Ion Torrent™ Oncomine™ Focus DNA Assay and the PGM™ platform. Important parameters for somatic mutations including the threshold for differentiation of a positive and a negative result, coverage, sensitivity, specificity, and limit of detection (LoD) were analyzed. Variant calls with coverage of <100x were found to be inaccurate. The limit of detection for identifying hotspot mutations was determined to be 4.3%. The sensitivity and specificity of the method were 96.1% and 97.8% respectively. No statistically significant difference was found between different gene targets in terms of performance of hotspot frequency measurement for the subset tested. In every validation study, the number of samples, the manner of sample selection, and the number and type of variants play a role in the outcome. Therefore, these parameters should be assessed according to the clinical needs of each laboratory undertaking the validation.

Coordinated Activities of Multiple Myc-dependent and Myc-independent Biosynthetic Pathways in Hepatoblastoma

Hepatoblastoma (HB) is associated with aberrant activation of the β-catenin and Hippo/YAP signaling pathways. Overexpression of mutant β-catenin and YAP in mice induces HBs that express high levels of c-Myc (Myc). In light of recent observations that Myc is unnecessary for long-term hepatocyte proliferation, we have now examined its role in HB pathogenesis using the above model. Although Myc was found to be dispensable for in vivo HB initiation, it was necessary to sustain rapid tumor growth. Gene expression profiling identified key molecular differences between myc^+/+ (WT) and myc^-/- (KO) hepatocytes and HBs that explain these behaviors. In HBs, these included both Myc-dependent and Myc-independent increases in families of transcripts encoding ribosomal proteins, non-structural factors affecting ribosome assembly and function, and enzymes catalyzing glycolysis and lipid bio-synthesis. In contrast, transcripts encoding enzymes involved in fatty acid β-oxidation were mostly down-regulated. Myc-independent metabolic changes associated with HBs included dramatic reductions in mitochondrial mass and oxidative function, increases in ATP content and pyruvate dehydrogenase activity, and marked inhibition of fatty acid β-oxidation (FAO). Myc-dependent metabolic changes included higher levels of neutral lipid and acetyl-CoA in WT tumors. The latter correlated with higher histone H3 acetylation. Collectively, our results indicate that the role of Myc in HB pathogenesis is to impose mutually dependent changes in gene expression and metabolic reprogramming that are unattainable in non-transformed cells and that cooperate to maximize tumor growth.

MAP3K11/GDF15 axis is a critical driver of cancer cachexia

BACKGROUND

Cancer associated cachexia affects the majority of cancer patients during the course of the disease and thought to be directly responsible for about a quarter of all cancer deaths. Current evidence suggests that a pro-inflammatory state may be associated with this syndrome although the molecular mechanisms responsible for the development of cachexia are poorly understood. The purpose of this work was the identification of key drivers of cancer cachexia that could provide a potential point of intervention for the treatment and/or prevention of this syndrome.

METHODS

Genetically engineered and xenograft tumour models were used to dissect the molecular mechanisms driving cancer cachexia. Cytokine profiling from the plasma of cachectic and non-cachectic cancer patients and mouse models was utilized to correlate circulating cytokine levels with the cachexia phenotype.

RESULTS

Utilizing engineered tumour models we identified MAP3K11/GDF15 pathway activation as a potent inducer of cancer cachexia. Increased expression and high circulating levels of GDF15 acted as a key mediator of this process. In animal models, tumour-produced GDF15 was sufficient to trigger the cachexia phenotype. Elevated GDF15 circulating levels correlated with the onset and progression of cachexia in animal models and in patients with cancer. Inhibition of GDF15 biological activity with a specific antibody reversed body weight loss and restored muscle and fat tissue mass in several cachectic animal models regardless of their complex secreted cytokine profile.

CONCLUSIONS

The combination of correlative observations, gain of function, and loss of function experiments validated GDF15 as a key driver of cancer cachexia and as a potential therapeutic target for the treatment and/or prevention of this syndrome.

18α-Glycyrrhetinic acid lethality for neuroblastoma cells via de-regulating the Beclin-1/Bcl-2 complex and inducing apoptosis

18α-Glycyrrhetinic acid (18-GA) is a known gap-junction inhibitor with demonstrated anticancer effects. However, the different modes of cell cytotoxicity for 18-GA remain to be characterized. In this study, 18-GA reduced the expression of cell-cell interaction proteins (N- and VE-cadherin), and led to a dose-dependent increase in cytotoxicity of the neuroblastoma cells tested, but was less toxic toward actively dividing human embryonic kidney cells. We found that 18-GA could induce both autophagy and apoptosis. 18-GA mediated autophagy was due to accumulation of Atg5, Atg7 and LC3II and degradation of p62. Individual siRNAs against Atg5 and Atg7 prevented autophagy and resulted in a further loss of viability with 18-GA. In addition, combination of 18-GA with autophagy inhibitor chloroquine produced a more significant cell death. This implied a pro-survival function for autophagy induction with 18-GA. 18-GA also led to the destabilization of Bcl-2/Beclin-1 interaction and cleavage of Beclin-1, a protein known to play role in apoptosis and autophagy induction. Treatment of cells by a pan-caspase inhibitor or a caspase-3 siRNA prevented a large portion of 18-GA mediated cytotoxicity, demonstrating that caspase-dependent apoptosis induction was responsible for most of the observed cytotoxicity. In terms of signaling, 18-GA led to reduced phosphorylation of all three classes of MAP kinases. Taken together, 18-GA or its pathways may lead to more effective, targeted therapeutics against neuroblastoma.

Placental origins of adverse pregnancy outcomes: potential molecular targets: an Executive Workshop Summary of the Eunice Kennedy Shriver National Institute of Child Health and Human Development

Although much progress is being made in understanding the molecular pathways in the placenta that are involved in the pathophysiology of pregnancy-related disorders, a significant gap exists in the utilization of this information for the development of new drug therapies to improve pregnancy outcome. On March 5-6, 2015, the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health sponsored a 2-day workshop titled Placental Origins of Adverse Pregnancy Outcomes: Potential Molecular Targets to begin to address this gap. Particular emphasis was given to the identification of important molecular pathways that could serve as drug targets and the advantages and disadvantages of targeting these particular pathways. This article is a summary of the proceedings of that workshop. A broad number of topics were covered that ranged from basic placental biology to clinical trials. This included research in the basic biology of placentation, such as trophoblast migration and spiral artery remodeling, and trophoblast sensing and response to infectious and noninfectious agents. Research findings in these areas will be critical for the formulation of the development of future treatments and the development of therapies for the prevention of a number of pregnancy disorders of placental origin that include preeclampsia, fetal growth restriction, and uterine inflammation. Research was also presented that summarized ongoing clinical efforts in the United States and in Europe that has tested novel interventions for preeclampsia and fetal growth restriction, including agents such as oral arginine supplementation, sildenafil, pravastatin, gene therapy with virally delivered vascular endothelial growth factor, and oxygen supplementation therapy. Strategies were also proposed to improve fetal growth by the enhancement of nutrient transport to the fetus by modulation of their placental transporters and the targeting of placental mitochondrial dysfunction and oxidative stress to improve placental health. The roles of microRNAs and placental-derived exosomes, as well as messenger RNAs, were also discussed in the context of their use for diagnostics and as drug targets. The workshop discussed the aspect of safety and pharmacokinetic profiles of potential existing and new therapeutics that will need to be determined, especially in the context of the unique pharmacokinetic properties of pregnancy and the hurdles and pitfalls of the translation of research findings into practice. The workshop also discussed novel methods of drug delivery and targeting during pregnancy with the use of macromolecular carriers, such as nanoparticles and biopolymers, to minimize placental drug transfer and hence fetal drug exposure. In closing, a major theme that developed from the workshop was that the scientific community must change their thinking of the pregnant woman and her fetus as a vulnerable patient population for which drug development should be avoided, but rather be thought of as a deprived population in need of more effective therapeutic interventions.

Sophoraflavanone G Induces Apoptosis in Human Leukemia Cells and Blocks MAPK Activation

Sophoraflavanone G (SG) was isolated from Sophora flavescens. Previously, we have found that SG is able to suppress the inflammatory response in lipopolysaccharide-stimulated RAW 264.7 macrophages. This study aimed to evaluate the effects of SG on apoptosis, and explore its molecular mechanism in human leukemia HL-60 cells. HL-60 cells were treated with various concentrations of SG (3–30 [Formula: see text]M). The viability of the HL-60 cells was assessed using the MTT method, and the nuclear condensation indicative of apoptosis was observed by DAPI fluorescence staining. In addition, apoptotic signal proteins were examined using Western blotting. The results showed that apoptosis, including DNA fragmentation and nuclear condensation, increased significantly in SG-treated HL-60 cells. SG activated caspase-3 and caspase-9, and downregulated Bcl-2 and Bcl-xL. SG also upregulated Bax and released cytochrome c from the mitochondria into the cytoplasm, enabling apoptosis via the mitochondrially-mediated “intrinsic” pathway. Additionally, SG was able to cleave poly (ADP-ribose) polymerase 1 and activate mitogen-activated protein kinase (MAPK) pathways. These results suggest that SG might increase the effect of apoptosis on HL-60 cells through caspase-3 activation, mitochondrial-mediated pathways, and the MAPK pathway.

Direct Attack on RAS: Intramolecular Communication and Mutation-Specific Effects

The crystal structure of RAS was first solved 25 years ago. In spite of tremendous and sustained efforts, there are still no drugs in the clinic that directly target this major driver of human cancers. Recent success in the discovery of compounds that bind RAS and inhibit signaling has fueled renewed enthusiasm, and in-depth understanding of the structure and function of RAS has opened new avenues for direct targeting. To succeed, we must focus on the molecular details of the RAS structure and understand at a high-resolution level how the oncogenic mutants impair function. Structural networks of intramolecular communication between the RAS active site and membrane-interacting regions on the G-domain are disrupted in oncogenic mutants. Although conserved across the isoforms, these networks are near hot spots of protein-ligand interactions with amino acid composition that varies among RAS proteins. These differences could have an effect on stabilization of conformational states of interest in attenuating signaling through RAS. The development of strategies to target these novel sites will add a fresh direction in the quest to conquer RAS-driven cancers. Clin Cancer Res; 21(8); 1810-8. ©2015 AACR. See all articles in this CCR Focus section, "Targeting RAS-Driven Cancers."

Polycomb Repressive Complex 2 Is a Barrier to KRAS-Driven Inflammation and Epithelial-Mesenchymal Transition in Non-Small-Cell Lung Cancer

Polycomb repressive complexes (PRC) are frequently implicated in human cancer, acting either as oncogenes or tumor suppressors. Here, we show that PRC2 is a critical regulator of KRAS-driven non-small cell lung cancer progression. Modulation of PRC2 by either Ezh2 overexpression or Eed deletion enhances KRAS-driven adenomagenesis and inflammation, respectively. Eed-loss-driven inflammation leads to massive macrophage recruitment and marked decline in tissue function. Additional Trp53 inactivation activates a cell-autonomous epithelial-to-mesenchymal transition program leading to an invasive mucinous adenocarcinoma. A switch between methylated/acetylated chromatin underlies the tumor phenotypic evolution, prominently involving genes controlled by Hippo/Wnt signaling. Our observations in the mouse models were conserved in human cells. Importantly, PRC2 inactivation results in context-dependent phenotypic alterations, with implications for its therapeutic application.

Rapid, Multiplexed Phosphoprotein Profiling Using Silicon Photonic Sensor Arrays

Extracellular signaling is commonly mediated through post-translational protein modifications that propagate messages from membrane-bound receptors to ultimately regulate gene expression. Signaling cascades are ubiquitously intertwined, and a full understanding of function can only be gleaned by observing dynamics across multiple key signaling nodes. Importantly, targets within signaling cascades often represent opportunities for therapeutic development or can serve as diagnostic biomarkers. Protein phosphorylation is a particularly important post-translational modification that controls many essential cellular signaling pathways. Not surprisingly, aberrant phosphorylation is found in many human diseases, including cancer, and phosphoprotein-based biomarker signatures hold unrealized promise for disease monitoring. Moreover, phosphoprotein analysis has wide-ranging applications across fundamental chemical biology, as many drug discovery efforts seek to target nodes within kinase signaling pathways. For both fundamental and translational applications, the analysis of phosphoprotein biomarker targets is limited by a reliance on labor-intensive and/or technically challenging methods, particularly when considering the simultaneous monitoring of multiplexed panels of phosphoprotein biomarkers. We have developed a technology based upon arrays of silicon photonic microring resonator sensors that fills this void, facilitating the rapid and automated analysis of multiple phosphoprotein levels from both cell lines and primary human tumor samples requiring only minimal sample preparation.

A-Raf: A new star of the family of raf kinases

The Ras-Raf-MEK-MAPK (mitogen-activated protein kinase)-signaling pathway plays a key role in the regulation of many cellular functions, including cell proliferation, differentiation and transformation, by transmitting signals from membrane receptors to various cytoplasmic and nuclear targets. One of the key components of this pathway is the serine/threonine protein kinase, Raf. The Raf family kinases (A-Raf, B-Raf and C-Raf) have been intensively studied since being identified in the early 1980s as retroviral oncogenes, especially with respect to the discovery of activating mutations of B-Raf in a large number of tumors which led to intensified efforts to develop drugs targeting Raf kinases. This also resulted in a rapid increase in our knowledge of the biological functions of the B-Raf and C-Raf isoforms, which may in turn be contrasted with the little that is known about A-Raf. The biological functions of A-Raf remain mysterious, although it appears to share some of the basic properties of the other two isoforms. Recently, emerging evidence has begun to reveal the functions of A-Raf, of which some are kinase-independent. These include the inhibition of apoptosis by binding to MST2, acting as safeguard against oncogenic transformation by suppressing extracellular signal-regulated kinases (ERK) activation and playing a role in resistance to Raf inhibitors. In this review, we discuss the regulation of A-Raf protein expression, and the roles of A-Raf in apoptosis and cancer, with a special focus on its role in resistance to Raf inhibitors. We also describe the scaffold functions of A-Raf and summarize the unexpected complexity of Raf signaling.

Protecting the normal in order to better kill the cancer

Chemotherapy is the only option for oncologists when a cancer has widely spread to different body sites. However, almost all currently available chemotherapeutic drugs will eventually encounter resistance after their initial positive effect, mainly because cancer cells develop genetic alterations, collectively coined herein as mutations, to adapt to the therapy. Some patients may still respond to a second chemo drug, but few cases respond to a third one. Since it takes time for cancer cells to develop new mutations and then select those life-sustaining ones via clonal expansion, "run against time for mutations to emerge" should be a crucial principle for treatment of those currently incurable cancers. Since cancer cells constantly change to adapt to the therapy whereas normal cells are stable, it may be a better strategy to shift our focus from killing cancer cells per se to protecting normal cells from chemotherapeutic toxicity. This new strategy requires the development of new drugs that are nongenotoxic and can quickly, in just hours or days, kill cancer cells without leaving the still-alive cells with time to develop mutations, and that should have their toxicities confined to only one or few organs, so that specific protections can be developed and applied.

FOXP4 modulates tumor growth and independently associates with miR-138 in non-small cell lung cancer cells

Family of forkhead box transcription factors, including forkhead box P4 (FOXP4), plays an important role in oncogenesis. The current study is to evaluate the role of FOXP4 in regulating human non-small cell lung cancer (NSCLC). Quantitative RT-PCR and Western blot were performed to evaluate the gene and protein expressions of FOXP4 in six NSCLC cell lines and 55 NSCLC patients. Lentivirus of small hairpin RNA (FOXP4-shRNA) was used to downregulate FOXP4 in NSCLC cell lines A549 and H1703 cells. Its effect on NSCLC growth, invasion, and cell cycle were evaluated by cell proliferation assay, migration assay, and cell cycle assay, respectively. Dual luciferase assay and Western blot were used to examine whether microRNA-138 (miR-138) was an upstream regulator of FOXP4. The dependence of FOXP4 on miR-138 associated signaling pathway was evaluated by ectopically overexpressing enhancer of zeste homolog 2 (EZH2), a known miR-138 target in NSCLC. FOXP4 was highly expressed in both NSCLC cell lines and NSCLC patients. FOXP4 downregulation by FOXP4-shRNA markedly reduced cancer cell growth and invasion, as well as induced cell cycle arrest in A549 and H1703 cells. MiR-138 was confirmed to be an upstream regulator of FOXP4 and directly regulated FOXP4 expression in A549 and H1703 cells. FOXP4 downregulation-mediated inhibition on cancer cell growth and invasion was independent on overexpressing EZH2, another direct target of miR-138 in NSCLC. Our data demonstrated that FOXP4 was a critical regulator in NSCLC and independently associated with miR-138 regulation.

Analysis of exosome release as a cellular response to MAPK pathway inhibition

Exosome size distributions and numbers of exosomes released per cell are measured by asymmetric flow-field flow fractionation/multi-angle light scattering (A4F/MALS) for three thyroid cancer cell lines as a function of a treatment that inhibits MAPK signaling pathways in the cells. We show that these cell lines release exosomes with well-defined morphological features and size distributions that reflect a common biological process for their formation and release into the extracellular environment. We find that those cell lines with constitutive activation of the MAPK signaling pathway display MEK-dependent exosome release characterized by increased numbers of exosomes released per cell. Analysis of the measured exosome size distributions based on a generalized extreme value distribution model for exosome formation in intracellular multivesicular bodies highlights the importance of this experimental observable for delineating different mechanisms of vesicle formation and predicting how changes in exosome release can be modified by pathway inhibitors in a cell context-dependent manner.

Gallbladder cancer in Chile: what have we learned?

PURPOSE OF REVIEW

Gallbladder cancer (GBC) should be considered an orphan disease in oncology and represent a unique carcinogenetic model. This review will analyse some of the current aspects of GBC.

RECENT FINDINGS

Chile has the highest incidence and mortality of GBC in the world. Most patients are diagnosed in advanced stages with few treatment options. During the last two decades, little progress has been made in early diagnosis and treatment. At the molecular level, recent access to next-generation sequencing and other techniques for detecting the mutations of multiple genes have made advances in this area.

SUMMARY

The use of therapies targeted according to the detection of specific molecular alterations is in the early stages of evaluation and could represent a significant advance in the treatment of a large number of patients from developing countries.

The identification of specific methylation patterns across different cancers

Abnormal DNA methylation is known as playing an important role in the tumorgenesis. It is helpful for distinguishing the specificity of diagnosis and therapeutic targets for cancers based on characteristics of DNA methylation patterns across cancers. High throughput DNA methylation analysis provides the possibility to comprehensively filter the epigenetics diversity across various cancers. We integrated whole-genome methylation data detected in 798 samples from seven cancers. The hierarchical clustering revealed the existence of cancer-specific methylation pattern. Then we identified 331 differentially methylated genes across these cancers, most of which (266) were specifically differential methylation in unique cancer. A DNA methylation correlation network (DMCN) was built based on the methylation correlation between these genes. It was shown the hubs in the DMCN were inclined to cancer-specific genes in seven cancers. Further survival analysis using the part of genes in the DMCN revealed high-risk group and low-risk group were distinguished by seven biomarkers (PCDHB15, WBSCR17, IGF1, GYPC, CYGB, ACTG2, and PRRT1) in breast cancer and eight biomarkers (ZBTB32, OR51B4, CCL8, TMEFF2, SALL3, GPSM1, MAGEA8, and SALL1) in colon cancer, respectively. At last, a protein-protein interaction network was introduced to verify the biological function of differentially methylated genes. It was shown that MAP3K14, PTN, ACVR1 and HCK sharing different DNA methylation and gene expression across cancers were relatively high degree distribution in PPI network. The study suggested that not only the identified cancer-specific genes provided reference for individual treatment but also the relationship across cancers could be explained by differential DNA methylation.

The epithelial to mesenchymal transition in pancreatic cancer: A systematic review

BACKGROUND/OBJECTIVES

The present article summarizes and analyzes the current knowledge about the role of the epithelial to mesenchymal transition (EMT) in the systemic invasiveness of pancreatic cancer.

METHOD

An electronic search of PubMed/MEDLINE, EMBASE, and the Web of Science was used to identify relevant original articles and reviews.

RESULTS

The EMT represents a key step during normal embryogenesis. However, increasing evidence reveals its essential role in the local progression and metastasis of pancreatic cancer. Areas of interest are the cross-linking between cells undergoing the EMT and pancreatic cancer stem cells, and the correlation between the EMT and chemoresistance to standard therapies. During carcinogenesis, malignant pancreatic cells at the primary site acquire the ability to undergo the EMT, a transformation associated with increased mobility. The reverse process at secondary sites, the mesenchymal to epithelial transition (MET), has devastating consequences, allowing neoplastic epithelial cells to invade surrounding tissues and spread to distant sites. Consequences of the EMT are the loss of E-cadherin expression and the acquisition of mesenchymal markers including fibronectin or vimentin. Detailed knowledge of the molecular processes underlying the EMT has opened possibilities for new therapeutic agents. These include an EMT approach for patients with early cancers, to prevent invasion and dissemination, and anti-MET therapy for patients with established metastasis.

CONCLUSIONS

The current literature shows a strong correlation between the EMT and the systemic aggressiveness of pancreatic tumors. Individualized therapy, targeting the process of EMT and its cross-linking with cancer stem cells, may increase survival of patients with pancreatic cancer.

TAp73 promotes anti-senescence-anabolism not proliferation

TAp73, a member of the p53 family, has been traditionally considered a tumor suppressor gene, but a recent report has claimed that it can promote cellular proliferation. This assumption is based on biochemical evidence of activation of anabolic metabolism, with enhanced pentose phosphate shunt (PPP) and nucleotide biosynthesis. Here, while we confirm that TAp73 expression enhances anabolism, we also substantiate its role in inhibiting proliferation and promoting cell death. Hence, we would like to propose an alternative interpretation of the accumulating data linking p73 to cellular metabolism: we suggest that TAp73 promotes anabolism to counteract cellular senescence rather than to support proliferation.